Extra-embryonic Wnt3 regulates the establishment of the primitive streak in mice

Abstract

The establishment of the head to tail axis at early stages of development is a fundamental aspect of vertebrate embryogenesis. In mice, experimental embryology, genetics and expression studies have suggested that the visceral endoderm, an extra-embryonic tissue, plays an important role in anteroposterior axial development. Here we show that absence of Wnt3 in the posterior visceral endoderm leads to delayed formation of the primitive streak and that interplay between anterior and posterior visceral endoderm restricts the position of the primitive streak. Embryos lacking Wnt3 in the visceral endoderm, however, appear normal by E9.5. Our results suggest a model for axial development in which multiple signals are required for anteroposterior axial development in mammals.

Optogenetic control of Wnt signaling for modeling early embryogenic patterning with human pluripotent stem cells

“…Targeting Wnt activation in cell subpopulations allowed us to model several key processes of early embryonic development. First, light stimulation of co-cultures mimicked the presentation of Wnt ligand in the epiblast, which occurs prior to primitive streak formation 9, 64, 65 . From studies of mouse embryogenesis and mESC model systems, Wnt signal induction from a localized source in extraembryonic tissue is thought to break anterior-posterior symmetry of the epiblast 9, 22, 29 , though the source of Wnt signaling remains ambiguous 64, 65 .…”

“…First, light stimulation of co-cultures mimicked the presentation of Wnt ligand in the epiblast, which occurs prior to primitive streak formation 9, 64, 65 . From studies of mouse embryogenesis and mESC model systems, Wnt signal induction from a localized source in extraembryonic tissue is thought to break anterior-posterior symmetry of the epiblast 9, 22, 29 , though the source of Wnt signaling remains ambiguous 64, 65 . Alternatively, cell-to-cell variability in the early embryo could also sensitize certain cells to a signal input or elicit spontaneous emergence of collective cell behavior 3, 18, 66 .…”

The novel 22 bp insertion mutation in a promoter region of the <i>PITX2</i> gene is associated with litter size and growth traits in goats

“…The significant effects of the 22 bp indel on reproductive traits might be explained by the function of the PITX2 gene: first, as a member of POU1F1-PROP1 pathway, the PITX2 gene regulates transcription and expression of other genes such as POU1F1, LHX3, PROP1, GH, and PRL (Zhang et al, 2015;Bertko et al, 2017;Zhao et al, 2017). Second, the PITX2 gene regulates Wnt/β-catenin pathway, affecting embryo implantation (Yusuke et al, 2006;Basu et al, 2013;Yeonsoo et al, 2015); therefore, this might be linked to litter size. Third, the PITX2 gene also regulates multiplets by influencing embryo polarity and axis formation (Angela et al, 2014).…”

Cables2 Is a Novel Smad2-Regulatory Factor Essential for Early Embryonic Development in Mice

“…Subsequently, in the 24 hours prior to gastrulation Wnt3 expression is initiated, first being detected in the PVE and then in the posterior epiblast by 6.0 dpc (Rivera-Pérez and Magnuson, 2005). Removal of this activity (Liu et al, 1999) prevents primitive streak formation whereas reduction of this activity (Tortelote et al, 2013; Yoon et al, 2015a) allows the streak to form but not elongate, resulting in impaired production of the tissues that constitute the A-P axis. Generally, when canonical Wnt ligands bind and activate their receptor, the intracellular molecule, β-catenin, is stabilised and translocates to the nucleus where it complexes with the Tcf family of DNA binding proteins to regulate transcription of Wnt target genes (Jamieson et al, 2012; Wang et al, 2012).…”